During the concrete curing process, chemical changes occur in the presence of water which ensure that the hardened concrete will be water-tight and durable. These chemical changes occur over a considerable period of time requiring that the concrete be kept wet during the curing period. The heat radiating from the concrete during the curing process evaporates the moisture in the concrete, inhibiting the chemical hardening process and compromising the strength and durability of the cured concrete. It is therefore necessary to contain the heat and moisture in the concrete long enough to permit the curing process to be sufficiently completed. This need for heat and moisture retention increases during cold weather applications.
Conventional methods of heat retention include the use of straw, sawdust and cloth blankets as insulating materials to prevent the premature drying of the concrete. These materials absorb water, are cumbersome and time consuming to remove from the concrete, cannot be effectively reused and may be subject to deterioration from the chemicals in the concrete. Moisture-impervious blankets using foam, fiberglass and like materials as insulation have been developed. However, fiberglass filling for curing blankets forms into small clusters or balls when wet, migrating to the corner of the blanket, thus destroying the insulating quality of the fiberglass. Open celled foam insulating material also absorbs water, which reduces the insulative efficiency of the foam material. Since the curing blankets which are the subject of the present invention are susceptible to accidental rips and tears, even blankets comprising moisture-impervious outer layers face the risk of water contacting the internal insulative layer or layers.
With decreasing temperatures the need for increased thermal insulation requires the use of additional layers of insulation resulting in insulation blankets of greater thickness when presently available blankets are used. These thicker insulation blankets can be relatively heavy and cumbersome to use, hampering portability. Additionally, their relative inflexibility reduces effectiveness when used on irregular concrete surfaces.
The present invention overcomes these and other problems inherent in existing multilayer insulation blankets. The present invention combines moisture-impervious outer layers and insulative layers with heat reflective layers that increase the thermal resistance of the blanket without increasing the blanket thickness.